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std::fill() algorithm

// (1)
template< class ForwardIt, class T >
constexpr void fill( ForwardIt first, ForwardIt last, const T& value );

// (2)
template< class ExecutionPolicy, class ForwardIt, class T >
void fill( ExecutionPolicy&& policy,
ForwardIt first, ForwardIt last, const T& value );
  • (1) Assigns the given value to the elements in the range [first; last).
  • (2) Same as (1), but executed according to policy.
    Overload Resolution

    These overloads participate in overload resolution only if std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>  (do C++20) std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>  (od C++20) is true.

Parameters

first
last

The range of elements to modify.

value

The value to assign.

policy

The execution policy to use. See execution policy for details.

Type requirements

ForwardItLegacyForwardIterator
value

Must be writable to first.

Return value

(none)

Complexity

Exactly std::distance(first, last) assignments.

Exceptions

The overloads with a template parameter named ExecutionPolicy report errors as follows:

  • If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the standard policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.
  • If the algorithm fails to allocate memory, std::bad_alloc is thrown.

Possible implementation

fill (1)

template<class ForwardIt, class T>
void fill(ForwardIt first, ForwardIt last, const T& value)
{
for (; first != last; ++first)
*first = value;
}

Examples

Main.cpp
#include <algorithm>
#include <iostream>
#include <vector>

int main()
{
std::vector<int> v {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};

std::fill(v.begin(), v.end(), -1);

for (auto elem : v)
std::cout << elem << ' ';
std::cout << '\n';
}
Output
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1
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std::fill() algorithm

// (1)
template< class ForwardIt, class T >
constexpr void fill( ForwardIt first, ForwardIt last, const T& value );

// (2)
template< class ExecutionPolicy, class ForwardIt, class T >
void fill( ExecutionPolicy&& policy,
ForwardIt first, ForwardIt last, const T& value );
  • (1) Assigns the given value to the elements in the range [first; last).
  • (2) Same as (1), but executed according to policy.
    Overload Resolution

    These overloads participate in overload resolution only if std::is_execution_policy_v<std::decay_t<ExecutionPolicy>>  (do C++20) std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>  (od C++20) is true.

Parameters

first
last

The range of elements to modify.

value

The value to assign.

policy

The execution policy to use. See execution policy for details.

Type requirements

ForwardItLegacyForwardIterator
value

Must be writable to first.

Return value

(none)

Complexity

Exactly std::distance(first, last) assignments.

Exceptions

The overloads with a template parameter named ExecutionPolicy report errors as follows:

  • If execution of a function invoked as part of the algorithm throws an exception and ExecutionPolicy is one of the standard policies, std::terminate is called. For any other ExecutionPolicy, the behavior is implementation-defined.
  • If the algorithm fails to allocate memory, std::bad_alloc is thrown.

Possible implementation

fill (1)

template<class ForwardIt, class T>
void fill(ForwardIt first, ForwardIt last, const T& value)
{
for (; first != last; ++first)
*first = value;
}

Examples

Main.cpp
#include <algorithm>
#include <iostream>
#include <vector>

int main()
{
std::vector<int> v {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};

std::fill(v.begin(), v.end(), -1);

for (auto elem : v)
std::cout << elem << ' ';
std::cout << '\n';
}
Output
-1 -1 -1 -1 -1 -1 -1 -1 -1 -1
This article originates from this CppReference page. It was likely altered for improvements or editors' preference. Click "Edit this page" to see all changes made to this document.
Hover to see the original license.